What is the radius of curvature of the parabola traced out by the projectile in the previous problem at a point where the particle velocity makes an angle θ/2 with the horizontal?

Here g is in downwards direction. Hence, some component to g will act as central force which will be changing at each point depending upon θ.



The horizontal component of velocity remains unchanged due to absence of force.



So we can write it as,




Using the expression for central force,





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